1. Field of the Invention
This invention relates to a cartridge valve, that is to a valve assembly comprising a cartridge housing containing a poppet type or like valve and which may include means forming a valve seat, the parts having a connected relation enabling installation and removal as a unit.
2. Description of the Prior Art
In a conventional cartridge valve, a projected valve housing is a part of a cap body incorporating external screw threads or the like by which the unit is secured within a cavity to control flow through intercommunicating fluid flow passages. An opening in the cap body allows a valve to be introduced into the valve housing and the latter may include a valve seat. Certain disadvantages inhere in this construction, including the need for three seals, one where the cap body enters the housing, a second to surround the valve housing between controlled passages and a third at the location of means to close the opening to the cap body. In addition, the one-piece construction of the cap body, valve housing and valve seat requires that the material of which the part is made be determined by the needed wear and resistance qualities of the most vulunerable portion. Thus, if the valve seat must be made of a relatively strong, wear resistant material because of the frequent contact made therewith by the valve this means that the cap body and entire valve housing must also be made of this same material. From a cost and weight standpoint there are many times when this is undesirable.
Insofar as is known, this problem has in the prior art been neither fully recognized nor adequately dealt with.